Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine 1108 _____________________________ _____________________________ Severe Sleep Problems among Infants A Five-Year Prospective Study BY MALENA THUNSTRÖM ACTA UNIVERSITATIS UPSALIENSIS UPPSALA 2002
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Comprehensive Summaries of Uppsala Dissertationsfrom the Faculty of Medicine 1108
Dissertation for the Degree of Doctor of Philosophy (Faculty of Medicine) in Paediatricspresented at Uppsala University in 2002
ABSTRACT
Thunström, M. 2002. Severe Sleep Problems among Infants. A Five-Year ProspectiveStudy. Acta Universitatis Upsaliensis. Comprehensive Summaries of Uppsala Dissertationsfrom the Faculty of Medicine 1108. 77 pp. Uppsala. ISBN 91-554-5201-9.
The aim of this thesis was to explore the prevalence of parentally experienced infant sleepproblems, with special interest in severe problems, in a total community sample of 2 518infants aged between 6 and 18 months. Factors associated with severe sleep problems weresought. Parents reported 16 % of the infants to have difficulties in falling asleep at night,and 30 % to have frequent night waking. Severe sleep problems were associated withfrequent night meals, psychosocial problems in the family, exhaustion and depression inthe mother, and parental stress. An association with infant difficultness, high activity andproblematic behaviour was also found.
In a five-year prospective study a group of children fulfilling specific criteria for severesleep problems in infancy (N=27) was followed after an interventional sleep programmeand compared with a control group regarding sleep characteristics, behaviour anddevelopment. One month after an interdisciplinary treatment programme, combiningbehavioural technique with family work, the average number of times the case babies wokeup had diminished from 6.0 to 1.8 times per night. A 92 % rate of improvement wasreported.
The changes were stable over time. Comparisons with the controls during five yearsrevealed no significant group difference in sleep characteristics. Concerning behaviour anddevelopment, however, there were significant differences. At the age of 5.5 years, seven ofthe children in the former sleep problem group met the criteria for the diagnosis ofattention-deficit/hyperactivity disorder. No control child qualified for the diagnosis.
Close follow-ups of infants with combined severe sleep and behavioural problems are recommended.
Printed in Sweden by Uppsala University, Tryck & Medier, Uppsala 2002
To all sleepy children
LIST OF PAPERSThis thesis is based on the following papers, which will be referred to in thetext by their Roman numerals:
I Thunström M.Severe sleep problems among infants in a normal population in Sweden:prevalence, severity and correlates. Acta Paediatrica 1999; 88: 1356-1363.
II Thunström M.Severe sleep problems among infants: family and infant characteristics.Ambulatory Child Health 1999; 5: 27-41.
III Thunström M.A 2.5-year follow-up of infants treated for severe sleep problems.Ambulatory Child Health 2000; 6: 225-235.
IV Thunström M.Severe sleep problems in infancy associated with subsequentdevelopment of attention–deficit/hyperactivity disorder at 5.5 years ofage. Acta Paediatrica. Accepted for publication.
V Thunström M.A 5-year follow-up of infants with severe sleep problems. Manuscript.
Reprints were made with the permission of the publishers.
CONTENTS
INTRODUCTIONGeneral background 7Maturation of sleep pattern in childhood 7Definition and classification of sleep disorders 9Assessment of sleep 11Epidemiology of sleep problems:prevalence, severity and persistence 12Correlates to disturbed sleep 14Treatment of sleep problems in childhood 15Attention-deficit/hyperactivity disorder (ADHD) and sleep 16Aims of the studies 21
METHODSDesign and subject selection 22 Study I 22 Study II-IV 22 Study V 24Procedures and measures 24
Study I 24Questionnaire on sleep and background factors 24Study II, III, V 25Questionnaires on sleep, family and infant characteristics and sleep diaries. 26Treatment programme 28Study IV 30Screening instrument for ADHD 30Assessment methods 31
Statistics 33
RESULTSPrevalence and classification of sleep problems 33Family and infant characteristics associated with severe infant sleep problems 36Short-term and long-term outcome of an interdisciplinary sleep treatment programme 44Factors associated with subsequent development of attention-deficit/hyperactivity disorder 48
DISCUSSIONGeneral discussion 52Validity of the results 58Conclusions and clinical implications 61ACKNOWLEDGEMENTS 63REFERENCES 65
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INTRODUCTION
General background
Sleep plays a major role in children´s well-being and is strongly influenced by
the child´s health status, psychological stress and family issues as well as by
multiple aspects of his or her culture and environment. Also, children´s sleep
patterns affect their well-being within the same wide range of health and
psychosocial phenomena.
Research has shown that sleep problems in infants and young children are
prevalent. Cross-sectional studies show that between 15 % and 35 % of all
children aged between 6 months and 5 years are reported by their parents to
show some type of sleep disturbance (22,69,76,98,100,102).
Before six months of age it is doubtful whether the label "sleep disturbance"
should be used, since during this period night waking is necessary in order to
fulfil the needs of frequent nutrition of the child. This is also the period
needed to reorganize the sleep pattern of the newborn to a more mature
pattern (85).
Maturation of normal sleep pattern in childhood
Sleep and sleep stages are defined by specific patterns of electro-
physiologically recorded brain activity, muscle tone and eye movements.
These polysomnographic measures divide sleep into two principal states:
sleep associated with rapid eye movements, "REM sleep", and sleep without
rapid eye movements, "non–REM sleep" (28). The REM component of sleep,
which dominates during the foetal period and the early months of life (50 %
of the sleep time), is thought to play a crucial role with regard to brain
8
development (105). The amount of REM sleep decreases to 30 % during the
first year of life and the REM–non REM state cycle also undergoes
maturational changes. In newborns and very young infants the cycle lasts
approximately 40 to 60 minutes. At two years of age the cycle has increased
to 75 minutes and continues to increase to an average of 84 minutes in 5-year-
olds (65).
A newborn baby does not distinguish day from night. Both sleeping and
eating take place around the clock, equally distributed over a 24-hour-period,
and the two processes are linked in time to each other. The baby wakes up to
eat and most often goes back to sleep while suckling and being fed at the
breast.
Gradually, in the course of the baby´s first year, a transition to a more regular
pattern of eating and sleeping takes place (10). The child acquires a pattern of
regular meals during daytime, a period of prolonged sleep during the night
and one, or most often two, short naps during daytime. Eating and sleeping
are increasingly separated, and, normally, the one-year-old child has grown
out of the habit of going to sleep while eating.
Temporary nightwaking in occasional periods of short duration is very
common among infants (42), but in the absence of any current physical
disease, a normal development and maturing of the central nervous system
(10) and normal parental handling (10,125), 90 % of one-year-olds sleep all
night (85). Prolonged and complicated sleep problems, however, have a
tendency to remain, especially from the first year of life to later childhood
(1,21,67,92). Moreover longitudinal studies (20,41,60,115) have indicated
that the attitudes and (over-) responsiveness of the parents to the signals of the
child in the parent–infant interaction could play a role in the maintenance of
the sleep problems of the child.
9
Other possible causative and maintaining mechanisms that have been studied
include factors in the genetic, somatic, psychological and psychosocial areas
(19-20,32,61,81,89). Prolonged, complicated sleep problems show a picture
of multiproblem, where the separate factors seem to amplify each other in
vicious circles. Factors affecting the child, the stressed and exhausted parents
and the social situation probably influence each other reciprocally and
interfere with the normal maturation of the sleep pattern.
Definition and classification of sleep disorders
Sleep problems in childhood are classified according to the International
Classification of Sleep Disorders: Diagnostic and Coding Manual (ICSD,
1990, American Sleep Disorder Association) into the following categories:
1. Dyssomnia
Dyssomnia comprises disorders that cause either insomnia (most common) or
excessive sleepiness (rare). Childhood insomnia is most often seen in limit-
setting sleep disorder (in which inadequate enforcement of bedtimes by the
parent results in the child stalling or refusing to go to bed at an appropriate
time) and in sleep-onset association disorder (in which the onset of sleep in
the child is impaired by the absence of a certain object or set of
circumstances). The first conditions is often called "sleep refusal" or "bedtime
struggles" ( a vivid expression) and has been reported in 5-10 % of a normal
population of preschool children (44). The second condition is often called
"frequent night-waking", when the child needs parental intervention of some
form several times every night to go back to sleep, and is seen in 15-20 % of
all children between 6 months and 3 years of age (44,98). Severity is
systematically classified along an axis in the ICSD, 1990, but this
classification and coding system has not been widely used in studies.
10
The ICSD criteria of severe sleep refusal (limit-setting sleep disorder) require
five or more episodes per night of stalling, calling out or leaving the bedroom.
The ICSD criteria of severe night waking problems (sleep-onset association
disorder) require a prolonged sleep latency and over three nightly wakings, or
two or three wakings, each lasting over 10 minutes or one lasting over 15
minutes. The awakenings occur at least five nights per week. Corresponding
detailed definitions for mild and moderate forms of the different sleep
disturbances are also found in the ICSD.
Nocturnal eating syndrome and schedule disorders are other types of
insomnia. Nocturnal eating (drinking) syndrome is characterized by recurrent
awakenings, with the inability to return to sleep without eating or drinking,
preferably breastmilk or formula. In schedule disorder the distribution of
sleep in terms of nap frequency and length across a 24-hour period, the sleep-
wake cycle, is altered in a way that comes into conflict with social
expectations and habits. The child´s sleep occurs at an inappropriate time.
Of course these definitions are cultural, as are the expectations of what is
"normal" infant sleep. Breast-fed babies throughout the world wake at night
and fall asleep at the breast, and in industrialized societies, in which the ICSD
1990 was written, we may have established inappropriate expectations from
experience with bottle-fed infants.
Nevertheless, parents of children with the above-mentioned sleep patterns
report themselves to be exhausted and in need of paediatric help.
Paediatricians, therefore, must have a good knowledge of infant sleep and
factors related to severe problems.
Excessive sleepiness is seen in the rare disorder, narcolepsy, and more often
in the obstructive sleep apnea syndrome.
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2. Parasomnia
Parasomnia comprises disorders that intrude into or occur during sleep that
are not, primarily disorders of the states of sleep and wakefulness per se.
Included here are confusional arousals, sleepwalking, sleep terrors, sleep
talking and sleep bruxism. Parasomnia is seen predominantly in children aged
3-12 years, where it encompasses 1-6 % of the population (7).
3. Medical/Psychiatric Sleep Disorders
Medical/Psychiatric Sleep Disorders comprise the medical and psychiatric
disorders commonly associated with sleep disturbance. In acute and chronic
illness (123), above all in diseases with pains or itching sensations, (38) sleep
problems are common, but the most difficult and prolonged sleep problems
are seen in mentally retarded children and children with autism, indicating a
common factor of dysfunction of the central nervous system (16).
Assessment of sleep
Clinical assessment of sleep disorders in children includes developmentally
appropriate history-taking of sleep-wake behaviour, including medical,
psychiatric as well as family and psychosocial issues (8,42,84). Physical
examination should be performed, with special attentiveness to signs of
diseases accompanied by pains, breathing difficulties or itching sensations.
Questionnaires and sleep logs or sleep diaries are valuable tools in the process
of detailed history-taking concerning sleep-wake complaints (8,121).
Actigraphy was developed as a practical measure for long-term quantification
of sleep/wake periodicity of movement, since both infants and children have a
lower activity level in sleep than in wakefulness. A small motion sensor and
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digital recorder is worn on a wrist and later downloaded into a computerized
analysis system. Advantages include noninvasiveness, ease of use and
automated scoring. Accuracy for sleep-wake discrimination has been reported
to be 85-93 % (111-112).
Audio and video recordings as well as polysomnography or other specialized
laboratory test are seldom used in infant studies. In clinical practice, selected
complicated cases are referred to sleep clinics with extended laboratory
devices (multichannel recordings, cardiorespiratory video systems, pulse
oximetry) (24,58).
Results from studies comparing parental reports with objective sleep
measures (109) show that parents are accurate reporters of sleep schedule
measures such as sleep onset and sleep duration. They overestimate, however,
the time that their infants spend in actual sleep and underestimate the number
of their night wakings. According to that result, short sleep duration and many
night wakings reported by parents of small infants should be regarded as a
minimum rather than be suspected of being an exaggeration by exhausted
care-takers.
Epidemiology of sleep problems: prevalence, severity
and persistence
Sleep disturbances in infants and young children, such as night waking and
bedtime struggles, are among the most common behaviour problems
encountered in paediatric practice. Night waking occurs in 15 % to 35 % of
children aged between 6 months and 5 years (17-18,21,59,69,76,94,98,102)
and the prevalence of bedtime struggles varies from 6 % to 16 % in the first 2
years (18,76,94) according to previous studies.
13
These earlier studies show that approximately one preschool child out of four
shows some kind of sleep problem, most often of short duration. A small
group of children, however, approximately 5 %, have more longlasting and
complicated sleep disturbances that can have an influence both on the health
of the child and on the function of the whole family.
Information on the long-term course of sleep problems in children (33,70-71),
and particularly in preschool children, is sparse. Richman, in her survey of
cross-sectional and longitudinal studies of disorders of initiating and
maintaining sleep (100), concludes that although correlations for waking
problems at different ages are reported low in schoolchildren (70), a
considerable number of preschool children have persistent sleep problems.
Especially during the first 2 to 3 years, the probability of continued waking is
high.
Infants who are irritable, sleep little and cry frequently during the early weeks
of life are more likely to be poor sleepers during the second year of life
(20,23). One survey (60) found that just under half (44 %) of those children
waking regularly at 6 months were still waking at 1 year. Furthermore almost
the same proportion (41 %) of the night wakers at 1 year were still waking at
18 months, and from 18 months to 2 years just over half of the children (54
%) continued waking. Conversely, 80 % to 90 % of nonwakers at these ages
continued to sleep well. Continuity after 2 years was less marked: 71 % of
night wakers at 2 years of age slept well at 3 years of age, and 86 % of wakers
at 3 slept well at 4.5 years of age.
Another community survey (103) found more problems. Of those with
bedtime problems at 3 years of age, 25 % still had problems at 4 years of age.
For night waking problems the figure was 36 %. Persistence of the same
problems in children 4 to 8 years of age was 40 % and 17 %, respectively.
14
There was a small core of persistent wakers, who Richman (100) speculates
could be particularly susceptible to irregular sleep patterns because of
neurophysiological or temperamental factors.
In another study (129) children with persistent sleep problems from 8 months
to 3 years of age (41 %), were found to be more likely to have behaviour
problems, especially temper tantrums and behaviour management problems,
than were children without persistent sleep problems. Finally, 84 % of sleep-
disturbed two-year-olds still had persistent sleep disturbances 3 years later in
a study (67) that found that persistent sleep disturbances had a significant
relationship with increased frequency of stress factors in the environment.
Different definitions of night waking and bedtime problems in different
studies contribute to generating different prevalence, severity and persistency
figures, but in summary, longlasting and complicated sleep problems seem to
have a tendency to remain, especially from the first year of life to later
childhood (1,21,67,92) and to be associated with behavioural problems
(119,129) as well as extreme tiredness and stress in the family (1,13,51,53).
Correlates to disturbed sleep
Factors in the genetic, somatic, psychological and psychosocial areas
correlate to disturbed sleep, as possible causative or maintaining mechanisms.
Genetic vulnerability, perinatal and medical disorders, temperamental
difficultness in the child, psychological (over-) responsiveness of the parents,
parental insecurity and stress, psychosocial problems, and development of
vicious circles (19-20,32,61,82,89) have been documented.
The effects of insufficient and disturbed sleep in children include daytime
behavioural problems. The children do not necessarily indicate their sleep loss
by obvious daytime somnolence (119). On the contrary, a hyperactive
15
behaviour might be the only indicator of sleep deprivation in a child, with
resolution of the behaviour problem following successful treatment of the
sleep disturbance (46). The effect of chronically disturbed sleep on the parents
is extreme tiredness (30,47,98,125,129), and several studies have shown that
severe sleep problems in infants and toddlers (pre-school children) are
associated not only with extreme tiredness and but also with psychiatric (73)
and physical illness in the family, especially depression in the mother. The
parents of children with severe sleep problems often seek help, and
associations with marital problems (19-20,82,89) and even child abuse have
been described (30,61,67). A heightened risk of later development of
behavioural problems and school difficulties also exists for children with
severe sleep problems (31-32,67,83).
Treatment of sleep problems in childhood
The methods suggested in the management of sleep difficulties range from
total acceptance (117) (usually meaning taking the child to the parents´ bed)
to ignoring all crying, with many variations in between. A number of
treatment programs, based on behavioural techniques, have been described in
the literature (73). These include establishing night-time routines and rituals,
reorganizing settling and waking times, minimizing night-time attention by
gradually withdrawing reinforcers, controlled crying by graduated extinction
(progressive delay responding) or straight extinction ("crying it out"), and
scheduled anticipatory waking where parents arouse and then resettle their
child 15-60 minutes before expected spontaneous awakings.
Studies of these techniques show high rates of improvement (80-90 %) when
used with support from a therapist (5,63,97,101,118). Sedatives are
commonly used and may be helpful in the short-term, but have been shown to
have long-term benefits only when used in combination with a behavioural
16
programme (51). The studies carried out to investigate the success of
behavioural programmes rarely have follow-up periods longer than three
months (47,56,73,79,81,126,128).
Attention-deficit/hyperactivity disorder (ADHD) and
sleep
Sleep problems are frequently reported in children and adolescents with
Parents perceive children with ADHD to have greater sleep difficulty than
normally developing children, and anecdotal reports of practising clinicians
suggest that the sleep of children with ADHD is often reported by parents to
have been disturbed from the very beginning of the child´s life, ever since
infancy: "He has never slept through a whole night in his entire life."
Previously, based on clinical experience, sleep disturbance among children
with ADHD was so widely presumed that it was included as one of the
diagnostic criteria for the disorder (DSM-III; American Psychiatric
Association, 1980). However, further research and re-examinations (14) led to
the exclusion of the sleep disturbance criterion in the 1987 version of the
DSM-III-manual. The present diagnostic criteria for ADHD (DSM-IV, 1994)
are presented in Box 1.
17
Box 1. Diagnostic criteria for attention-deficit/hyperactivity disorder (DSM-IV, 1994)*
A. Either (1) or (2):
(1) six (or more) of the following symptoms of inattention have persisted for at least6 months to a degree that is maladaptive and inconsistent with developmentallevel:
Inattention(a) often fails to give close attention to details or makes careless mistakes in
schoolwork, work, or other activities(b) often has difficulty sustaining attention in tasks or play activities(c) often does not seem to listen when spoken to directly(d) often does not follow through on instructions and fails to finish schoolwork,
chores, or duties in the workplace (not due to oppositional behaviour orfailure to understand instructions)
(e) often has difficulty organizing tasks and activities(f) often avoids, dislikes, or is reluctant to engage in tasks that require sustained
mental effort (such as schoolwork or homework)(g) often loses things necessary for tasks or activities (e.g., toys, school
assignments, pencils, books, or tools)(h) is often easily distracted by extraneous stimuli(i) is often forgetful in daily activities
(2) six (or more) of the following symptoms of hyperactivity-impulsivity havepersisted for at least 6 months to a degree that is maladaptive and inconsistentwith developmental level:
Hyperactivity(a) often fidgets with hands or feet or squirms in seat(b) often leaves seat in classroom or in other situations in which remaining
seated is expected(c) often runs about or climbs excessively in situations in which it is
inappropriate (in adolescents or adults, may be limited to subjective feelingsof restlessness)
(d) often has difficulty playing or engaging in leisure activities quietly(e) is often "on the go" or often acts as if "driven by a motor"(f) often talks excessively
Impulsivity(g) often blurts out answers before questions have been completed(h) often has difficulty awaiting turn(i) often interrupts or intrudes on others (e.g., butts into conversations or games)
A. Some hyperactive-impulsive or inattentive symptoms that caused impairment werepresent before age 7 years.
B. Some impairment from the symptoms is present in two or more settings (e.g., at school[or work] and at home).
18
C. There must be clear evidence of clinically significant impairment in social, academic,or occupational functioning.
D. The symptoms do not occur exclusively during the course of a PervasiveDevelopmental Disorder, Schizophrenia, or other Psychotic Disorder and are not betteraccounted for by another mental disorder (e.g., Mood Disorder, Anxiety Disorder,Dissociative Disorder, or a Personality Disorder).
* American Psychiatric Association. Diagnostic and statistical manual of mental disorders, 4th ed (DSM-IV). Washington, DC: American Psychiatric Press, 1994.
A detailed and systematic review of empirical research published since 1970
on sleep disturbances in children with ADHD, encompassing sixteen relevant
studies, was published in 1998 by Corkum, Tannock and Moldofsky (35).
They found that although subjective accounts of sleep disturbances in ADHD
were prevalent (based on sleep diaries, questionnaires and interviews),
objective verification of these disturbances (by polysomnographs, actigraphy
or video) was less robust (13). In fact, the only consistent objective findings
were that children with ADHD displayed more movements during sleep but
did not differ from normal controls in total sleep time (39,78,121). Further
studies by the same authors have confirmed this picture (34) and pointed to a
complex relationship between sleep problems and ADHD. In a recent study
(80) the conclusion was drawn that although subjective sleep difficulties are
common in ADHD youths, they are frequently accounted for by comorbidity
and pharmacotherapy.
However, when convincing evidence exists of sleeplessness in an overactive
child, attempts should be made to increase or improve the sleep because, in
some cases, the ADHD features may be the result of poor sleep (37,121). The
effects of sleep loss in children include tiredness, difficulties with focused
attention, low threshold to express negative affect (irritability and easy
frustration), and difficulty modulating impulses and emotions (37). In some
cases these symptoms may resemble ADHD. This has been reported in
children with obstructive sleep apnoea, with improvement of behaviour
following treatment (53).
19
ADHD-associated sleep disturbances may be improved by medication with
clonidine
(93,127). Improvements can also be achieved by administration of stimulant
drugs late in the day (29,93,121,127) even if insomnia secondary to stimulant
medication is a well-known adverse effect in some children (15,35,120).
of stimulant treatment for childhood attention-deficit problems have,
however, showed that for this patient group in general, early awakenings and
disturbed sleep tend to occur less frequently with stimulant treatment than at
baseline, i.e. without treatment (49).
In their review of the literature (35), Corkum, Tannock and Moldofsky
conclude that the exact nature of the sleep problems in children with ADHD
remains to be determined. Many relevant issues need new and better
methodological approaches. One interesting field is Periodic Limb
Movements in Sleep (PLMS) in children with ADHD, which has been
recently studied by Picchietti et al (90-91). PLMS are repetitive flexions of
the toes, feet, legs, thighs and/or the arms which recur periodically during
sleep. Sleep disruptions often accompany these movements, which in studies
using polysomnography and electromyography have been shown to be more
prevalent in children with ADHD than in control children.
Studies using retrospective data on sleep patterns in infancy among children
with ADHD are scarce. Trommer et al (124) compared 48 schoolchildren with
ADD (with and without hyperactivity) with 30 controls using retrospective
parental questionnaires which covered the ages 0 to 12 months and 1 to 4
years. The ADD children were reported to have had more frequent arousals
than the controls had both in the first year and from 1 to 4 years. However,
there is an obvious risk of selective memory bias in such studies.
20
Other prospective studies than the one included in this thesis on children with
severe sleep problems in infancy, concerning the risk of later development of
inattention and hyperactivity-impulsivity, have to our knowledge not yet been
performed.
21
Aims of the studies
The aims of this 5-year prospective study were:
1. to provide epidemiological data on infant sleep-wake characteristics and
the prevalence and severity of sleep problems in a general population, as
perceived by parents
(Study I),
2. to explore medical, psychological and psychosocial child and family
characteristics associated with severe infant sleep problems (Studies I och
II),
3. to investigate the changes in sleep in a group of severely sleep-disturbed
infants after a specific treatment programme combining behavioural
technique and interdisciplinary family work (Study III),
4. to prospectively follow and compare a group of children identified with
severe sleep problems in infancy with a control group regarding the
development of symptoms of attention-deficit/hyperactivity disorder
(ADHD) (Study IV) and regarding further sleep pattern (Studies III and
V),
5. to explore factors in infancy which are associated with subsequent
development of ADHD in later childhood (Study IV).
22
METHODS
Design and subject selection
Study I
A total community sample of 2 518 infants aged between 6 and 18 months
were approached using a parental questionnaire. The response rate was 83 %.
Data from the collection procedure point to a non-selective drop-out, not
reflecting presence or absence of sleep problems. Severe sleep problems as
defined by the ICSD were found in 129 of the children (6.2 %) who were
studied in detail, with the rest of the population as controls.
Studies II-IV
Those 6 to 12 month-old children in the community sample who fulfilled
specific inclusion criteria for severe and chronic sleep problems (N = 27)
created the case group.
Inclusion criteria were:
- the child should be reported by parents to have a prolonged sleep latency
and over three nightly wakings occurring at least five nights per week. This
pattern of disrupted sleep should have prevailed for a period of at least
6 months.
- infant age between 6 and 12 months at inclusion in the study. (The reason
for restriction of the study to this age group was limited resources and the
ambition to investigate all children with severe sleep problems in a specific
population with home visits by the same paediatrician).
23
- full-term pregnancy with a birth weight of greater than 2 500 grams and
gestational age of at least 37 weeks.
- the parents should report the need of help. (This criteria turned out to be
unnecessary. All parents of children with the above-mentioned sleep
problems reported themselves to be in need of help. This was true even for
the non-European parents in this group, who co-slept with their breastfed
child according to their cultural norms. They all reported much need for
help with their child´s sleep within the context of the Swedish
industrialized society).
- the parents should be able to communicate in Swedish or English.
The exclusion criterion was:
- signs of significant organic causes of the sleep problem identified by
hospital examinations and laboratory tests.
Among the 28 families with infants fulfilling the set inclusion criteria,
(i.e. 2 % of the sample of 1 259 children aged between 6 and 12 months), one
family was not able to participate because they moved to another part of the
country. The other 27 families agreed to participate in the study. Sixteen of
the children were boys, eleven girls. None of them fulfilled the exclusion
criteria. All were basically healthy and went further in the study.
A control group was matched with regard to age and sex. The infant of a
particular sex who fell next in age sequence to the case infant in the Child
Health Center (CHC) register was chosen as a control. A further criterion was
that no sleep problems were reported on the questionnaire. Of 33 families
contacted, 27 agreed to participate.
24
Study V
In addition to the original control group, an extended control group was
created from the questionnaire – study I, consisting of four control children
for each case child. The controls were matched for age and sex, had no
reported sleep problems in the questionnaire at 6 to 12 months and were still
living in Sweden five years later.
Procedure and measures
Study 1
In January 1996 data were collected in a parent population study in the urban
district of Uppsala (the fourth largest municipality in Sweden). A
questionnaire, constructed especially for this study, was sent to all parents
with an infant born during the period from July 1994 to July 1995.
Questionnaire on sleep and background factors
The instrument covered the following areas: social and demographic
background, pregnancy and birth, sleep-wake characteristics, parental
behaviour, and feeding problems.
Most items in the questionnaire had a 5-step response scale with verbal
definitions of each scale step. A few items had response categories with
yes/no answers. The items were constructed in close accordance with the
ICSD classification in addition to subjective parental rating scales of the
severity of the problem. No validation process was possible for these scales,
since the explicit aim of the questions was to measure early sleep problems as
perceived by parents.
25
Study II, III, V
A home visit was scheduled when parents had received information about the
study and agreed to participate in the research project.
The author, who is a clinically active a paediatrician, interviewed the parents
about the infant’s sleep characteristics and family members’ previous and
present state of health. The infant’s interaction with the parents and normal
activity were observed, and the development of the child was assessed. A
thorough somatic examination of the child was also performed. Information
about demographic variables, perceptions of parenting and infant
temperament, life events and social support was collected in a questionnaire
that the mothers filled in after the home visit. The following week the parents
kept a special Sleep Diary of the sleep of their child. This diary was brought
to the special CHC center where the parents of the children in the case group
received advice, counselling and support in the form of a behavioural training
programme, in order to overcome the sleep problems of their child. The sleep
programme was carried out as detailed later. The paediatrician was of course
aware of the group status of the families visited. In order to reduce the
possible influence of this, the assessments of the psychosocial problems were
compared with data from the CHC and the medical records of all the children.
This was done by two independent assistants who were blind to infant group
status.
One month after inclusion in the study the parents in the problem group were
sent another 7-day sleep diary and a general questionnaire about their opinion
of the help received. At one year, two and a half years and five years,
respectively, from inclusion, contact was made by mail, and a questionnaire
and sleep diary were filled in by the parents of both the problem group and
the control group. For ethical reasons the study design did not include any
placebo intervention group (i.e. untreated children in the problem group), as
26
studies of behavioural programmes have shown high rates of improvement
(80-90 %) (5,63,97,101,118).
Questionnaires on sleep, family and infant characteristics, and
sleep diaries
The home visit covered questions about sleeping characteristics and the state
of health of the family and comprised open-ended questions, scored on
yes/no, 3-step or 5-step response scales. Sleep characteristics were covered in
five questions that allowed a classification of the child’s sleep
pattern/problem according to the definitions of ICSD, 1990, in a 24-hour
recall of the infant’s sleep, and questions about the circumstances surrounding
getting the child to sleep. The following week the parents filled in a special
Sleep Diary of the sleep of their child in which the amount of night and
daytime sleep was recorded. In addition information was recorded about clock
time into bed, sleep latency, settling time, arousals (time and length), morning
wake time, in bed awake – and out of bed time, and day time naps (time and
length). All data were measured in minutes. Parental and sibling sleep
problems during infancy were also probed. In order to assess the infant’s
general development, the procedure used at the CHC was employed (National
Board of Health and Welfare, 1991), including an assessment of gross and
fine motor skills, as well as language, social, cognitive, and neurological
development. Development was rated on 5-step scales ranging from very late
for age to well above chronological age level.
The health status of the family was addressed by two questions about medical
pregnancy and delivery complications, and by four concerning the family’s
contact with medical care and health status during the infant’s lifetime.
Answers to questions about health were supplemented with information from
medical records.
27
Assessment of the psychosocial situation of the family was based on self-
disclosure during the medical interview (e.g. reports of unemployment,
financial restraints, conflicts between the infant’s parents, conflicts with the
infant’s grandparents, family health problems, substance abuse). Psychosocial
problems were rated by the author as none, minor or major. In order to reduce
the possible influence of the authors´ knowledge of the group status of the
child, the assessments of psychosocial problems were compared with data
from the CHC and medical records. This was done by two independent
assistants who were blind to infant group status. The findings showed an
interrater correlation of r = 0.95 when one assistant’s ratings of the listed
observations of the paediatrician (author) was compared with the other
assistant’s ratings of data from the CHC and medical records. The interrater
correlation between the author’s ratings and the assistant’s ratings was
r = 0.98.
Information about family demographic variables (ethnicity, age and
education, employment, housing and financial situation, and number of
children) was gathered by a questionnaire mothers completed after the home
visit. Maternal perceptions of parenting were obtained through semi-
structured questions scored by mothers on 5-step response scales. The
inventory, a revised Swedish version of R. Abidin´s Parenting Stress Index
(PSI; Abidin, 1990) (2,74,130), contained 34 items in 5 subscales that focused
on parental feelings of competence/incompetence, restriction by parental role,
social isolation, spouse relationship problems, and health problems.
To measure infant temperament, the Baby Behaviour Questionnaire (BBQ)
and the Toddler Behaviour Questionnaire (TBQ) (54-55) were used. In the
methodological work with the TBQ, a construct corresponding to difficultness
has been developed, consisting of low manageability as the most important
28
characteristic. This construct, based on 5-step response scales, was used in the
present study.
The occurrence of infants’ problematic behaviour during the previous month
was reported by mothers in the home interview. Questions in the interview
were related to sleeping habits, thumb or dummy sucking, screaming and
whining, shyness, activity, restlessness and lack of concentration, temper
tantrums and the mothers’ perception of the child as troublesome, difficult to
handle. Maternal ratings on 2-point response scales (yes, no) were used.
Treatment programme
The methods used were based on the following premise which was explained
to parents: "During the night all children have some spells of light sleep
during which they easily wake. The problem is not that the child wakes up but
that it cannot slip back to sleep without the help of a parent rocking or feeding
it. The way the baby is settled to sleep in the evening will be its preferred way
of returning to sleep after natural wakings. In order to have a child that returns
to sleep by itself, you have to accustom it to settle on its own".
The programme included:
Controlled crying
Controlled crying, or more positively called controlled comforting, implies
that the parent spends a few minutes settling the child, then leaves it for
gradually increasing lengths of time with brief and warm, but firm,
reassurance and resettling in between, yet avoiding taking the child out of its
cot. No feeding is given, and the child should be drowsy but still awake when
put into bed. The intervals between reassurance increase from initially one
minute up to five minutes at most. This procedure was used (if needed) every
29
time the baby was settled by day or night, and whenever it woke and cried at
night. Consistency was emphasized. A nurse and a child psychologist
supported the parents by daily telephone calls for 1-2 weeks and then tried to
help them to develop confidence in the programme and to manage on their
own.
Day and night routines
Overtired babies do not sleep well at night. Two daytime sleeps of about 1-1½
hours were encouraged, together with a regular pattern of feeds, play times
(with plenty of parental involvement) and sleep. The precise times could be
varied somewhat to fit in with each family situation, but it was important to
ensure that feeds and sleep were separated.
General help and information were given as appropriate, e.g. about nutrition,
feeding practices and play techniques. The great range of normal behaviour
and development was discussed with the parents.
Parents were encouraged to be agreed about the programme management and
to find ways to get support and time out for themselves in order to maintain
the energy needed to care for a baby or toddler. Problems such as relationship
stresses, social problems, depressive moods and parental health problems
were addressed if appropriate.
Medication
Five children with deeply depressed and exhausted parents were given
sedatives (alimemazine) for two weeks at the beginning of the programme, in
combination with the behavioural programme, in order for the parents to be
able to sleep directly and thereby regain some mental strength.
30
Study IV
A screening procedure for ADHD was carried out 4.5 to 5 years after
inclusion in the study, when the children had reached the age of 5.5 years. In
case of screen posivity, further assessment methods were used to diagnose
ADHD.
Screening instrument for ADHD
The screening procedures were identical for all children in the study and
comprised the following:
(i) a Parent Psychomotor Questionnaire (PPQ) containing four questions
pertaining to the child’s psychomotor development for completion by parents
and rated on a scale of normal/abnormal (95).
(ii) a previously validated Preschool Questionnaire (PSQ) comprising six
items pertaining to the child’s attentional, motor, language and perceptual-
conceptual capacity for completion by the preschool teacher and rated on a
scale of normal/abnormal (96).
(iii) a motor examination, performed by a nurse who had received special
training. The examination was carried out at the CHC, according to a
standardized screening of motor abilities that comprised six items rated on a
scale of normal/abnormal (48).
The screening procedures were in accordance with the battery recommended
by the Swedish National Board of Health and Welfare for screening for minor
neurodevelopmental/psychiatric disorders in preschool children at the CHCs
(72,96).
31
The criteria for screen positivity were: (a) one or more abnormal scores on
either the PPQ or the PSQ in combination with one or two abnormalities on
the motor examination or (b) three abnormalities on the motor examination.
Children not fulfilling these criteria in the screening procedure were
considered screen-negative. The criteria for screen-positivity were chosen so
as to identify children with ADHD as well as those with other
neurodevelopmental and neuropsychiatric problems (72).
The screening methods used in this study have been psychometrically
examined in previous Swedish studies (45,48,50,96) and have been found to
have good inter-rater and test-retest reliability.
Assessment methods
The assessment methods used for diagnosis comprised a detailed history,
psychiatric and neurodevelopmental examination, neuropsychological
assessment and speech/language evaluation.
The first assessment was performed by the local multidisciplinary district
CHC teams including the local psychologists, speech therapists,
physiotherapists and paediatricians outside the original sleep study
organization. Those teams were thus unaware of the group status of the
children examined. The psychological examination included an assessment of
development with Griffiths´ Developmental Scale II (52) in addition to a
detailed history and a clinical neuropsychological assessment of symptoms of
inattention, hyperactivity, impulsivity and behavioural problems. The speech
therapists used clinically accepted assessment methods of language
comprehension, phonological and grammatical problems, and the
physiotherapists administered the Scandinavian motor-perceptual scale MPU
32
(57). The local paediatrician performed a paediatric physical examination of
the child with the focus on neurological functioning.
The second examining paediatrician with special training in child
neuropsychiatry (author M.T.) was unaware of the results of the previous
assessment performed by the local team members while performing the
second step in the assessment procedure, a home visit.
A medical, developmental and behavioural history was taken at a home
interview with the parents, using a standardized interview schedule. The
criteria for ADHD according to the DSM-IV were checked during this
interview, and each criterion was rated as 'definitively met', 'possibly met' or
'not met'. Inter-rater reliability of results obtained at this type of ADHD
interview is excellent (72).
Routine paediatric psychical examination and a brief neurodevelopmental
examination in accordance with the method outlined by Gillberg et al. (48)
were also performed at the home visit. Inter-rater reliability for this
standardised assessment is good to excellent with values of Pearson r ranging
from 0.68 to 1.00 for individual items (50).
Diagnosis
A comprehensive diagnosis was made in each case after all neuropsychiatric
assessments had been completed on the basis of the available information.
The diagnosis ADHD was set in children meeting the criteria for this
diagnosis of the DSM-IV (Box 1).
33
Statistics
For analysis of the data, the statistical program SAS (113) was used in all
studies. Group comparisons for dichotomous variables were executed with
Chi-square analyses or Fisher’s exact test (two-tailed) when an expected cell
value was less than 5. For variables with 3-,5- or 7-step response scales,
comparisons were made with t-tests. In group comparisons, the more
conservative alpha level of 0.01 was used because of the large number of
tests.
RESULTS
Prevalence and classification of sleep problems (Study I)Sleep problems: Descriptive dataPrevious sleep problems, irrespective of duration or type, were reported for
48.3 % of the total child population. At the time of inquiry, 40.8 % of the
children were reported to have episodes of evening sleep refusal, including
minor and transient problems. The sleep refusal was considered a severe or
very severe problem by 3.8 % of the parents.
With respect to night-waking, 62.3 % of the children had current problems,
irrespective of severity and duration. The night-wakings were considered a
severe or very severe problem by 5.6 % of the families.
Table 2 gives descriptive data for sleep refusal and night-waking problems
measured with parental rating scales. Table 1 gives descriptive data classified
according to the operational definitions of ICSD. The frequency of severe
sleep refusal and severe night-waking problems in the total child population
varied between 3.8 % and 6.2 % in these measurements, with the parents
34
being slightly more tolerant in their judgement and opinions than the ICSD
scales.
Table 1. Percentages of infants that fulfilled the ICSD criteria of severe sleep refusal
(limit-setting sleep disordera) and severe nightwaking problems (sleep-onset association